Refractory composition



Patented June-12, 1923.

UNITED STATES 1,458,726 PATENT OFFICE.

JOHN L. OHMAN, DECEASED, LATE OF NIAGARA FALLS, NEW YORK, BY CHARLES A. WHITE, ADMINISTRATOR, OF BUFFALO, NEW YORK, ASSIGNOR TO BUFFALO RE- FRACTORY CORPORATION, OF BUFFALO, NEW YORK, CORPORATION 01?" DEIaA- 'wAnn.

REFRACTORY COMPOSITION.

No Drawing. Original application filed November 1, 1917, Serial No. 199,792. Patent No.

Divided and this application filed October 9, 1920. Serial No. 415,878.

To all whom it may concern:

Be it known that JOHN L. OHMAN, deceased, late a subject of the King of Sweden and a resident of Niagara Falls, county of 6 Niagara, and State of New York, by

CHARLES A. WHITE, his administrator, residing at Buffalo, county of Erie, State of New York, did invent a certain new and useful Refractory Composition, of which the fol- 10 lowing is a full, clear, and exact description.

This is a divisional application based on the ori inal disclosure made in application Serial No. 199,792 filed November 1, 1917, now Patent No. 1,356,939, for patent on refractory materials.

The general object of this invention has been to provide a refractory composition whichshall be elastic and very durable, thus preventing cracking, disintegrating, corrodmg, and oxidizing.

Another object has been to provide a refractory composition which shall be-easily and cheaply manufactured and one in which, in order to permanently bind the constituent materials together, it shall be unnecessary to raise the composition to the temperature of recrystallization.

Another object has been to provide a composition which shall resist chemical action and one which shall greatly increase the life of the articles which are made therefrom.

In the specification, this composition is described as applied to the construction of a crucible; it being obvious that it can be used for making any heat resisting articles; such as, fire bricks, retorts, muflies, refractories, furnace cores, tubes, combustion boats, fur nace linings, and heat resisting cements.

It is well known to those skilled in the art, that crucibles in common use (known to the trade as graphite crucibles)have been, formed either of plumbago or graphite, and preferably German clay, and a slight addition of silica in the form of sand (sometimes fire sand). These graphite crucibles oxidize and disintegrate quite rapidly both from the action of the furnace fires on the outside of the crucibles, and, on the inside, from the effects (termed scalping) and also to crumble. The life of a gra hite crucible,.therefore, is comparatively s ort. -This composition is made up of the follow ng elements in the proportions named: Silicon carbide, substantially 24 parts. Crystalline alumina, substantially 22 parts. Silicon oxide, substantially 22 parts. Ctrystalllne graphite, substantially 25 par s. D

Binder, substantiall 7 parts.

In the above formu a, substantially e ual parts of silicon carbide, crystalline alumina, and silicon oxide, are set forth, it being understood, however, that these elements are the equivalent of each other and that the total, 68 parts, of the entire composition may be divided between these three elements in 70 any desired manner. As is well known in the art, fire sand is not a chemically inert refractory electric furnace product, and, therefore, it is not considered to be the equivalent of the silicon carbide, crystalline alu- 7 mina, or silicon oxide.

As a binder for my composition, clay may be used, or if desired, a carbonizing binder (such as tar, pitch or molasses) may be used as a binding agent. However, when using a carbonizing binder, a fusion mixture is preferably used for protecting the composition against oxidation and disintegration.

A clay, having a low fusion point, may be used as such fusion agent. In place of using clay as a protector or flux, I may substitute a metallic ornon-metallic salt (such as borax or feldspar), oxide (such as oxide of iron) or other suitable fusion mixture. It will be understood "that a combination of different salts or different oxides, or a combination of both of these fusion agents may be used. It is necessary, however, when carbonizing binders are used, to increase the percentage of such binders.

In making a crucible, the ingredients are thoroughly mixed and placed upon a potters wheel, where the crucible is spun in the usual manner, or, if desired, the mass may be pressed or molded into shape. After the crucible is formed by spinning, pressing or molding, it is dried and then baked at a low temperature (approximately .100 0 C.) After baking the crucible is ready for use.

other, thus giving a certain amount of flexibility to the whole body of the crucible,

which enables it to withstand sudden changes in temperature without cracking.

As is well known, silicon carbide, crystalline alumina, and silicon oxide, are each a product of the electric furnace, and are, respectively, chemical compounds of silicon and carbon, aluminum and oxygen, and silicon and oxygen. Each of these materials has a very high fusion point; is very inert chemically, as is graphite; is a good conductor of heat; has an extremely low coefficient of expansion; and shows practically no oxidation under extreme heat. 1

These materials, therefore, mixed with crystalline graphite make a very suitable refractory article, which is a good conductor of heat, is elastic, tough, strong, and highly resistant to oxidation and the action of fluxes. The use of a metallic or non-metallic salt, oxide or other fusion mixture, is to assist in the binding of the materials and to form a protecting coating around the graphite and the carbonizing binder, when such binder is used.

While certain proportions of the different ingredients have been set forth, it is obvious that they may be varied somewhat with out departing from this invention, as, for

' instance, when making a very small crucible a large percentage of the refractory base may be used; but, when making large crucibles, the proportion of the graphite will be increased to give the finished product sufficient flexibility so that it will expand and contract without fracture.

While the term crystalline is used in this application, as applied to graphite, it is to be understood that this term also in cludes what is known in the trade as flake graphite, which is the equivalent of crystalline graphite.

Having thus described this invention,

what is claimed is:

1. A refractory composition for heat resisting articles, comprising silicon carbide, crystalline alumina, and silicon oxide, and crystalline graphite.

2. A refractory composition for heat resistin articles, comprising silicon carbide, crysta line alumina, and SlllCOIl oxide, crystalline graphite, and a binder.

3. A refractory composition for heat re- ,and its chemical esa-72a sisting articles, comprising silicon carbide, crystalline alumina, and SlllCOl'l oxide, crystalline graphite, and a salt.

4. A refractory composition for heat resisting articles, comprising silicon carbide, crystalline alumina, and silicon oxide, crystalline graphite, and clay.

5. A refractory composition for heat resistin articles, comprising silicon carbide, crysta line alumina, and silicon oxide, crystalline graphite, and a carbonizing binder.

6. A refractory composition for heat resisting articles, comprising silicon carbide, crystalline alumina, and silicon oxide, crystalline graphite, a binder, and a salt.

7 A refractory composition for heat resistin articles, comprising silicon carbide, crystalline alumina, and silicon oxide, crystallifiiie graphite, a carbonizing binder, and a sa 8. A refractory composition for heat resisting articles, comprising silicon carbide, crystalline alumina, and silicon oxide, crystalline graphite, a carbonizing binder, and c ay.

9. refractory composition for heat resisting articles, comprising substantially 68% of a mixture of silicon carbide, crystalline alumina, and silicon oxide, substantially 25% of crystalline graphite, and substantially 7% of a binder.

10. A refractory composition for heat re- Y sisting articles, comprising substantially 68% of a mixture of silicon carbide, crystalline alumina, and silicon oxide,.s'ubstantially 25% of a carbonizin binder and a clay, the clay having a low sion point and acting-as a protector.

11. A refractory composition for heat resisting articles, comprising substantially 68% of a mixture of silicon carbide, crystalline alumina, and silicon oxide, substantially 25% of crystalline graphite, and substanltially 7% of a carboni'zing binder and a sa t.

12. A rcfractory composition for heat resisting articles, comprising substantially 24% of silicon carbide, 22% of crystalline alumina, and 22% of silicon oxide, substantially 25% of crystalline graphite, and substantially 7% of a binder.

13. A refractory composition for heat resisting articles, comprising substantially 24% of silicon carbide, 22% of crystalline alumina, and 22% of silicon oxide, substantially 25% of or stalline graphite and 7% of a carbonizing inder and a clay, the clay having a low fusion point and acting as a protector.

In testimony whereof, I have hereunto signed my name.

CHARLES A. rrE,

Administrator of the estate of John L. Oh-

man, deceased, 

